This invention relates to a magnetic recording/playback apparatus and, more particularly, to a magnetic recording/playback apparatus in which cassette and tape loading operations are made possible using a single drive motor.
A magnetic recording/playback apparatus (hereinafter referred to as a VTR, or video tape recorder) has a basic construction which includes a cassette loading mechanism, a tape loading mechanism, a tape feed mechanism and three motors for driving respective ones of these mechanisms. Since the arrangement using these three motors is such that space is required on the VTR chassis in order to install the motors, the VTR is large in size and high in cost, the latter because the motors themselves are costly. For this reason, attempts have been made to reduce the number of motors. One such example is disclosed in the specification of Japanese Patent Application Laid-Open (KOKAI) No. 61-289572. In this example of the prior art, two pulleys are secured to the output shaft of one motor, the rotational torque of the motor is transmitted to the cassette loading mechanism through one pulley, a belt and a clutch, and to the loading mechanism through the other pulley and its associated belt. During cassette loading, the rotational torque of the motor is transmitted to both the cassette and tape loading mechanisms. During tape loading, the clutch is released to interrupt the transmission of torque to the cassette loading mechanism. In other words, the clutch is engaged or disengaged in response to a signal produced when the cassette is received in the VTR at a predetermined position or when the cassette is ejected from the predetermined position, thereby controlling the transmission of rotational torque from the motor to the cassette loading mechanism.
Certain difficulties are encountered in the example of the prior art described above. Specifically, if the cassette becomes stuck during cassette loading, for example, rotational torque will continue to be transmitted from the motor to the tape loading mechanism irrespective of the fact that the pulley and belt on the cassette loading side are slipping. Consequently, when the angle of rotation of a cam exceeds a predetermined value, this is taken as meaning that the cassette has been received at its predetermined position and, hence, a tape pull-out section begins operating This is undesirable because the cassette is stuck and not actually in place, as mentioned above. Furthermore, to eject the cassette, the tape loading mechanism is actuated to re-accommodate the tape within the cassette, after which the cassette loading mechanism is actuated to eject the cassette. However, at the changeover in operation from tape loading to cassette loading, high-speed rotation on the side of the tape loading mechanism is transmitted to the side of the cassette loading mechanism via the clutch, as a result of which an offset in the engagement timing of the clutch occurs. When the VTR is operated the next time, this offset or shift in timing can cause the clutch to be released, resulting in starting of the tape loading operation, even though the cassette has not been received at its predetermined position.